Mesh Generation Overview

Use the mesh tool to extract a surface and prepare a mesh for use in Voyager or for .stl download.

Summary

Last Updated November 2024

The Mesh tool in the Author toolbar allows a mesh to be extracted from volumetric data such as Reconstructions and ROIs. Use this tool to precisely define the boundary of your part. Meshes have utility across a number of workflows including:

1. Precise dimensioning within Voyager.
2. Mesh comparisons between an instance of a part and
   1. An ideal part instance.
   2. A CAD file.
3. Export for use in external tools.

Workflow Parameters

The mesh workflow contains a number of parameters which are each detailed below. 

Parameter Overview

1. Volume Selection
2. Use ISO-50 threshold
3. Isolate largest body and remove residual material.
4. Mesh Threshold
5. Smoothing Factor
6. Generate from Full Data
7. Decimate Mesh
8. Create Mesh

Volume selection

Select from available volumes within your project to generate a mesh from.

Use ISO-50 threshold

ISO-50 Thresholding is an automatic threshold selection method that is appropriate for low attenuation, mono-material parts. Use ISO-50 thresholding to accurately define the boundary between part and air for this class of parts. This extracted mesh will be automatically accurate for use in dimensioning and other workflows. 

Read this support article for a detailed explanation of how to use ISO-50 on appropriate parts to achieve accurate dimensional analysis within Voyager.

https://support.lumafield.com/iso-50-and-mesh-snapping

Isolate largest body and remove residual material

When a mesh is extracted from a volume, the mesh is treated as a monolithic block of data. Any data above the threshold will be included, and any data below the threshold will be removed, with no consideration of topology or connectedness. 

Isolate largest body takes the resulting mesh and analyzes the mesh to remove anything except the largest body in the results. This programmatically removes anything that is not geometrically connected to the largest body and removes it before returning your data. 

Use this tool to remove porosity from meshes, or to remove residual data that you don't need in downstream processes. 

Mesh Threshold

The mesh threshold is the most important single parameter in the mesh generation workflow, because the threshold defines the surface of your mesh. 

Currently, if your part is not a low attenuation, mono-material part, Voyager does not have an automatic thresholding method that produces accurate results. 

Adjust the threshold and monitor your viewport until your part surface is accurately reflected in the preview. Iterate on the threshold by generating multiple meshes in series to understand what different threshold values produce. 

If you have applications that require precise, accurate surfaces, there are options for you including calibrating the mesh thresholding settings to a known physical dimension on your part in question.

Smoothing Factor

Smoothing is detailed in this support document. Smoothing is a valuable tool to reduce surface complexity and produce simplified geometry for use in various downstream workflows. Smoothing can also reduce mesh artifacts in high-noise scans. 

https://support.lumafield.com/mesh-smoothing

Generate from Full Data

When generating meshes, Voyager works off of the data that it has available at any given time. By default, meshes are generated from the resolution of the data of the object that you see in Voyager, which is a reduced-size volume that we generate so that we can serve CT data in your web browser. 

If you want the best-possible accuracy in your mesh, however, enable "Generate from full data" and Voyager will generate your mesh using the full-resolution volume that we have stored in the cloud. This will create much higher fidelity meshes that can show full resolution detail across the entire mesh surface. 

Regardless of the increase in runtime, meshes generated from full data provide incredible insight into the surface details of your part. 

Decimate Mesh

When Voyager generates a mesh, it decimates it as the final step in order to provide usable data for use in a web-browser, or for import into other environments. Lumafield knows that each customer has different needs for their meshes, so we have provided a decimation tool that puts you in charge of what resolution the resulting mesh will be. 

The range of options corresponds to different use-cases, and ranges from: 0.5mb - 10,000 Polygons to 1.0gb - 20,000,000 Polygons.

Voyager itself can display most meshes produced in this range, but at the high end, we may encounter hardware limitations depending upon the specifications of your computer. In this case, we will provide the option to download the mesh rather than view in Voyager.

Choosing appropriate mesh decimation is highly dependant on your needs downstream. Experiment with different settings to find the mesh decimation factor that works for you. 

Create Mesh

When all of your parameters are established, use this button to request a mesh generation from Voyager. Meshes typically return in 1-5 minutes, unless you have "Generate from full data" enabled, in which case meshes may take up to 1 hour to return.